1. Field of the Invention
The present invention relates to a fringe field switching (hereinafter, simply referred to as “FFS”) mode liquid crystal display, and more particularly to an FFS mode liquid crystal display capable of improving driving mura and luminance non-uniformity.
2. Description of the Prior Art
A method for fabricating an ultra-FFS mode liquid crystal display may be described as follows, with reference to FIGS. 1A and 1B. Herein, FIG. 1A is a plan view of a conventional ultra-FFS mode liquid crystal display, and FIG. 1B is a sectional view thereof.
As shown in FIG. 1A, according to the conventional ultra-FFS mode liquid crystal display, a gate line 11 and a data line 15 are aligned to cross perpendicular to each other on a lower substrate 10. Then, a first ITO electrode 17 is aligned in a region defined by the gate line 11 and the data line 15 and a second ITO electrode 19 for a pixel electrode is aligned while overlapping with the first ITO electrode 17. The orientation of liquid crystal is aligned at 0 degrees. Herein, the second ITO electrode 19 for the pixel electrode includes a plurality of slit patterns 19a, in which the slit patterns 19a are formed in an inclined manner, so that the edge sections of the slit patterns 19a have a wedge shape.
Also, as shown in FIG. 1B, an upper substrate 20 is disposed opposite to the lower substrate 10, while being spaced from the lower substrate 10 by a predetermined interval, and a black matrix 21 is formed on the upper substrate 20. Herein, the edge sections of the slit patterns 19a having the wedge shape in the second ITO electrode 19 for the pixel electrode, which overlaps with the black matrix 21, are disposed in a transmission region spaced by a length of ‘a’ to the outside from an edge section of the black matrix 21. That is, the slit patterns 19a of the second ITO electrode 19 are disposed while not overlapping with the black matrix 21.
Owing to such a construction, when liquid crystal molecules are twisted by an electric field, upper liquid crystal molecules (a color filter substrate) and lower liquid crystal molecules (an array substrate) are twisted in opposite directions from each other, thereby compensating for chromatic shift toward a bluish color or a yellowish color, which is caused by dielectric anisotropy of the liquid crystal.
According to the conventional FFS mode liquid crystal display fabricated the above-mentioned method, since an overlapped region between electrodes is very wide, layers such as an insulation layer may be deteriorated due to long-period electrical operations, which results in inferior afterimages.
In order to correct such a disadvantage, various shapes and structures of electrodes have been studied and proposed.
However, according to conventional FFS pixels, the edge sections of the slit patterns having the wedge shape, which forms a non-uniform electric field (i.e. which causes distortion in the operation of liquid crystal) are not disposed in the black matrix but located in the actual transmission region.
As a result, such a relationship between the pixel wedge and the black matrix causes transmittance reduction and luminance non-uniformity due to an alternation operation between them, so that the characteristics of manufactured goods are deteriorated.